Center core for a laminated coupling

ABSTRACT

A laminated coupling used to connect a helicopter rotor arm to a rotor blade includes a pair of spaced end bushings interconnected by an endless belt. A pair of annular clips encircle the belt adjacent the bushings to define a center section of the coupling having generally parallel sides defining an opening between them. A core piece composed of a plurality of relatively rotatable laminations is disposed in the opening between the clips to maintain separation of the clips and to permit twisting of the coupling about an axis extending through the bushings.

United States Patent lnventor 172] Peter Brooks South Bend, Ind.

[2| 1 Appl No. 879,674 [22] Filed Nov. 25, I969 [45 I Patented Sept. 7,1971 [73] Assignee The Bendix Corporation [54] CENTER CORE FOR ALAMINATED COUPLING 8 Claims, 2 Drawing Figs.

[52] US. Cl 74/581 [51] Int. Cl G05g 5/00 [50] Field of Search 74/581,

[56] References Cited UNITED STATES PATENTS 2/1968 Ditlinger 3,475,98811/1969 Ditlinger et al.

Primary Examiner-Milton Kaufman Assistant Examiner-F. D. ShoemakerAttorneys-C. F. Arens and Flame, Arens, Hartz, Smith and ThompsonABSTRACT: A laminated coupling used to connect a helicopter rotor arm toa rotor blade includes a pair of spaced end bushings interconnected byan endless belt. A pair of annular clips encircle the belt adjacent thebushings to define a center section of the coupling having generallyparallel sides defining an opening between them. A core piece composedof a plurality of relatively rotatable laminations is disposed in theopening between the clips to maintain separation of the clips and topermit twisting of the coupling about an axis extending through thebushings.

CENTER CORE FOR A LAMINATED COUPLING BACKGROUND OF THE INVENTION Thisinvention relates to a laminated coupling.

Couplings of the type having a pair of end bushings interconnected by alaminated belt, also know as tie bars, have been widely used in recentyears to secure helicopter rotor arms to the rotor blades. Suchcouplings must be able to withstand relatively large axially appliedforces, yet must also be relatively light in weight. These couplingsmust also have low torsional stiffness, since helicopter designrequirements necessitate that the couplings be able to twist through anangle as large as 90. without offering high resistance. The couplingsalso must have along service life while operating in an adverseenvironment, such as in an oil bath.

SUMMARY OF THE INVENTION Therefore, an important object of my inventionis to increase the oil resistance, heat resistance, and wear resistanceof laminated couplings.

Another important object of my invention is to decrease the torsionalstiffness of laminated couplings.

Yet another important object of my invention is to provide a tie barthat accomplishes all of the above objects yet having weight andstrength characteristics as good as or better than existing designs.DESCRIPTION OF THE DRAWINGS FIG. 1 is a horizontal cross-sectional viewof a laminated coupling know in the prior art; and

FIG. 2 is a fragmentary cross-sectional view, similar to FIG. 1, of alaminated coupling made pursuant to the teachings of my presentinvention. DETAILED DESCRIPTION Referring now to the drawing, elementssubstantially the same in both of the FIGS. employ the same referencecharacter. A laminated coupling includes a pair of spacedapart endbushings l2 and 14, each of which includes and opening 16, 18 extendingtherethrough that is adapted to receive a pin (not shown) for securingthe coupling 10 to surrounding structure. Each of the bushings 12, 14 isof the type disclosed in US. Pat. No. 3,388,615, owned by the assigneeof the present invention, and includes an upper flange (not shown) and alower flange 19, 21 which define channels 20, 22 around the periphery ofthe bushings l2 and 14 that receive an end portion 24, 26 of an endlessbelt 28 that extends around each of the bushings 12 and 14. The belt 28is composed of several layers of wirelike filaments integrated by apolyurethane adhesive, as disclosed in U.S. Pat. No. 3,460,628, assignedto the assignee of the present invention.

Belt 28 further includes a pair of opposed side portions 30, 32 whichwith the bushings l2, l4 define an opening 34 in the coupling 10. A pairof clips 36, 38 encircle the side portions 30, 32 at points adjacenteach of the bushings l2 and 14 to draw the center sections 40, 42 of theside portions 30, 32 toward each other, so that the center sections 40and 42 are generally parallel to one another. Each of the clips 36 and38 consists of two half clips 44, 45 and 46, 47 to facilitateinstallation of the clips 36, 38 on the tie bar. The outer periphery ofeach clip 36, 38 is provided with a circumferentially extending channel48, 50 which is adapted to receive wire filaments 52, 54 which arewrapped circumferentially around the clips 36, 38 to hold the half clipstogether.

When the coupling 10 is installed on an aircraft, the axially directedtension force P acting on the coupling results in a pair of forcecomponents acting on the clips 36 and 38. One of the force componentsP,acts radially outwardly from the center of the coupling and tends toseparate the half clips 44, 45 and 46, 47. This force is resisted by thecircumferential wraps of filament wire 52, 54. Another force, P tends toslide the clips 36 and 38 toward the center of the bar. This force mustalso be resisted, but since the coupling must have low torsionalstiffness, a solid, nondeformable member cannot be used as a core pieceto maintain separation of the clips. Therefore, keyways 56 and 58 areprovided in each of the clip assemblies 36 and 38 that receive matingcross pins 60 and 62 that extend through the opening 34. In the priorart device, a deformable urethane core piece 64 is interposed betweenthe cross pins 60 and 62 to maintain proper separation between thelatter. The urethane core is strong enough to prevent the clips, fromslid ing, yet is deformable so that the coupling may twist, and performsquite satisfactorily in all but extremely adverse operating conditions.However, when the coupling illustrated in FIG. 1 is used at hightemperatures in an oil bath, the urethane core piece 64 has a tendencyto extrude between the cross pins 60, 62 and the belt 28, thus reducingthe optimum life of the coupling.

In the improved coupling illustrated in FIG. 2, the urethane core 64 isreplaced by an elongated core piece 65 which includes a plurality ofsolid, nondeformable laminations 66 disposed between the cross pins 60and .62. Each of the laminations 66, and each of the pins 60 and 62, hasa central bore 68 extending therethrough which slidably receives a rod70. Each of the laminations 66 is permitted to rotate with respect tothe pins 60 and 62 and with respect to all of the other laminations 66.Preferably, each of the laminations 66 may be coated with a low frictionmaterial, such as Teflon, to facilitate relative rotations between thelaminations, and to reduce heat buildup in the coupling due to frictioncaused by relative rotation of the laminations. The ends 72, 74 of therod 70 are preferably enlarged to prevent accidental withdrawal of therod.

Therefore, it can be seen that the laminations act as a solid member toproperly position the cross pins 60, 62 and therefore, the clips 36, 38on the coupling 12. However, since the laminations 66 may rotate on therod 70, the coupling has a very low torsional stiffness and is able totwist about an axis extending through the bushings l2, 14.

I Claim:

1. A coupling comprising:

a pair of spaced-apart bushings adapted to be connected to surroundingstructure;

an endless belt interconnecting said bushings;

said belt having a pair of opposed end portions extending around saidbushings and a pair of spaced side portions defining the sides of anopening in said coupling;

an elongated core piece disposed in said opening extending between saidside portions;

said core piece including a plurality of interconnected membersrotatable relative to one another about an axis extending through saidbushings to permit twisting of the coupling about said axis.

2. The invention of claim 1; and

means carried by said belt adjacent each of said bushings for drawingsaid side portions together to present a section of said couplingbetween said means having generally parallel sides;

said core piece extending between said means.

3. The invention of claim 2;

said means being a pair of clips encircling said belt; and

a pair of cross pins extending through said opening and engaging saidclips;

said core piece being disposed between said cross pins to therebyprevent movement of the cross pins relative to the belt.

4. The invention of claim 3:

said members being a plurality of laminations disposed between saidpins;

each of said pins and each of said laminations having a central openingextending therethrough; and

an assembly rod extending through each of said pins and each of saidlaminations.

5. A laminated coupling comprising:

a pair of spaced-apart bushings adapted to be connected to surroundingstructure;

an endless belt encircling said end bushings;

said belt consisting of a series of layers of a filament materialintegrated by an adhesive material;

means carried by said belt adjacent each of said bushings defining asection of said belt between said means having spaced, generallyparallel sides defining the sides of an opening through the belt; and

members disposed in said opening between said means for locating thelatter on said belt;

said members being rotatable relative to one another about an axisextending through said bushings to permit twisting of the coupling aboutsaid axis.

6. The invention of claim 5:

said means being a pair of clips encircling said belt;

a pair of cross pins extending through said opening;

each of said cross pins engaging one of said clips to prevent the latterfrom sliding toward the other clip.

7. The invention of claim 6:

said members being a plurality of laminations disposed between saidpins; and

means for interconnecting the laminations and the pins 8. The inventionof claim 7:

each of said pins and each of said laminations having a central openingtherethrough;

said last-mentioned means being an elongated assembly rod;

said rod extending through each of said central openings.

1. A coupling comprising: a pair of spaced-apart bushings adapted to beconnected to surrounding structure; an endless belt interconnecting saidbushings; said belt having a pair of opposed end portions extendingaround said bushings and a pair of spaced side portions defining thesides of an opening in said coupling; an elongated core piece disposedin said opening extending between said side portions; said core pieceincluding a plurality of interconnected members rotatable relative toone another about an axis extending through said bushings to permittwisting of the coupling about said axis.
 2. The invention of claim 1;and means carried by said belt adjacent each of said bushings fordrawing said side portions together to present a section of saidcoupling between said means having generally parallel sides; said corepiece extending between said means.
 3. The invention of claim 2; saidmeans being a pair of clips encircliNg said belt; and a pair of crosspins extending through said opening and engaging said clips; said corepiece being disposed between said cross pins to thereby prevent movementof the cross pins relative to the belt.
 4. The invention of claim 3:said members being a plurality of laminations disposed between saidpins; each of said pins and each of said laminations having a centralopening extending therethrough; and an assembly rod extending througheach of said pins and each of said laminations.
 5. A laminated couplingcomprising: a pair of spaced-apart bushings adapted to be connected tosurrounding structure; an endless belt encircling said end bushings;said belt consisting of a series of layers of a filament materialintegrated by an adhesive material; means carried by said belt adjacenteach of said bushings defining a section of said belt between said meanshaving spaced, generally parallel sides defining the sides of an openingthrough the belt; and members disposed in said opening between saidmeans for locating the latter on said belt; said members being rotatablerelative to one another about an axis extending through said bushings topermit twisting of the coupling about said axis.
 6. The invention ofclaim 5: said means being a pair of clips encircling said belt; a pairof cross pins extending through said opening; each of said cross pinsengaging one of said clips to prevent the latter from sliding toward theother clip.
 7. The invention of claim 6: said members being a pluralityof laminations disposed between said pins; and means for interconnectingthe laminations and the pins.
 8. The invention of claim 7: each of saidpins and each of said laminations having a central opening therethrough;said last-mentioned means being an elongated assembly rod; said rodextending through each of said central openings.